Display gated sections in course outline, navigation and in the course
when user has met prerequiste condition.

WL-1273, WL-1317

This reverts commit 4312c0e7.

Inspired by: http://eldarion.com/blog/2013/02/14/entry-point-hook-django-projects/
Moves startup code to lms.startup and cms.startup, and calls the startup
methods in wsgi.py and manage.py for both projects.

Commands like the following were not working correctly:
```
$ python manage.py lms runserver --lms
```